1. Field of the Invention
The present invention relates to a method for working the end portion of a roof molding for use in an automobile.
2. Description of the Related Prior Art
As shown in FIG. 16, in many cases, a roof molding 60 is mounted on the roof 51 of an automobile 50. As can be seen from FIG. 17 which shows part of the roof 51 with the roof molding 60 removed from the automobile 50, in order to conceal the connecting lines of the portions of a roof panel 52 and an outer panel 53 where they are connected integrally with each other, the roof molding 60 is mounted or fitted into a groove 54 which is formed in the connecting portions of the two roof and outer panels 52 and 53.
The roof molding 60, as can be seen from FIG. 18, is composed of a leg portion 61 and a decorative portion 65 which is disposed on the upper end of the leg portion 61, while the decorative portion 65 is used as the design surface of the roof molding 60; and, the roof molding 60 is mounted in such a manner that the leg portion 61 thereof is inserted into the groove 54 and the decorative portion 65 thereof covers the groove 54. Also, in many cases, a metal core member 63 is embedded into the leg portion 61 in such a manner as to extend along the longitudinal direction thereof in order not only to mount and hold the roof molding 60 in the groove 54 of the above panel connecting portions correctly but also to reduce the linear expansion of the leg portion 61. In FIG. 18, reference character 66 designates a lip (a fin piece) which is formed on the two side surfaces of the lower portion of the leg portion 61 in such a manner as to extend along the longitudinal direction thereof, in order to assure the fixing of the leg portion 61 to the grooves 54.
By the way, if the two end portions of the groove 54 of the connecting portion of the roof 51 are molded by pressing with the same depth as the central portion of the groove 54, then there is caused a crack in the upper corner portions 55 of the groove 54. For this reason, the groove 54 is formed in such a manner that it becomes gradually smaller in depth toward the ends thereof. Accordingly, if, as the roof molding 60, there is used a molding which can be obtained simply by cutting a molding blank member 60a consisting of a long extruded molding into a given length, then the lower end of the leg portion 61 interferes with the body of the automobile, which makes it impossible to mount the roof molding 60 into the groove 54 correctly. Therefore, recently, there has been proposed a method in which, as shown in FIG. 18, an end portion 62 matched to the depth of the end portion of the groove 54 is injection molded in the end portion of the molding blank member 60a cut to a given length.
However, in the roof molding 60 with the injection molded end portion 62, on the surface of the end portion of the roof molding 60, in particular, between the molding blank member 60a and end portion 62, there is produced a joint line 67 which can impair the appearance of the roof molding 60. Also, because the main body portion of the roof molding 60 composed of the molding blank member 60a is different in the resin shrinkage ratio from the injection molded end portion 62, there is caused a crack in the portion of the joint line 67 due to the difference between the thermal shrinkage amounts between them or due to the degradation thereof; and, in the worst case, the end portion 62 and molding blank member 60a can be separated from each other.
Also, partly because the groove 54 of the roof 51 is mostly curved in the neighborhood of the end portions thereof in the plane direction thereof as well as in the height direction thereof, and partly because such lip 66 or the like as in the molding blank member 60a is not present in the injection molded end portion, the end portion 62 as it is cannot be fixed along the groove 54 fitly, but there can be produced a gap between the one side portion of the end portion 62 and the side surface of the groove 54, or the end portion 62 can be warped from the groove 54. To solve these problems, conventionally, the end portion 62 is fixed to the end portion of the groove 54 with pressure sensitive adhesive double coated tape or adhesive agents. However, it takes time and labor to carry out such assemblies, which increases the cost thereof; and also, the adhesive strength of the adhesive tape or adhesive agents can be rather weak, so that, as time passes, the end portion 62 becomes easy to warp from the groove 54.
By the way, to make the end portion 62 to follow the above-mentioned curved shape of the end portion of the groove 54, there can be imagined a method in which, when the end portion 62 is injection molded, a projection is formed on the side surface of the end portion 62 to thereby make constant the distance between the side surface of the groove 54 end portion and the side surface of the end portion 62, or a method in which a clip is provided in the end portion of the groove 54 and there is formed in the end portion 62 a portion to be engageable with a pawl formed in the present clip. In these cases, however, the strength of the connecting portions between the end portion 62 and molding blank member 60a is weak and, therefore, if the end portion 62 is mounted into the groove 54 of the roof 51 in such a manner that the end portion 62 is curved, then there is a danger that the end portion 62 can be separated in the joint line 67. Also, to avoid this problem, there can be imagined another method in which only the projection is injection molded locally in the molding blank member 60a cut to a given shape. Even in this case, however, the adhesive strength between the projection and molding blank member 60a is weak and, therefore, there is a danger that the end portion 62 can be peeled or slipped off at such projection portion from the molding blank member 60a.